My sister does that with her game chickens an it works fine for her but she has great woodland for them. You could give them several grains an hay if your ground is not as good. But your going to have better results with a prepared feed unless you really know what your doing.

We have a 2 acre meadow that backs up to a undeveloped 100 acre Girl Scout Camp woods, with a creek at the bottom of the hill. So I'm assuming they will have pretty varied forage available. Lots of bugs, which I assume could replace the protein they would have gotten from the mash? Is it safe to just go by the color of the yokes to determine if they are getting a nutrient dense diet? Thanks

We have tried several feeding programs, ranging chickens will typically not put on as much weight as those that don't move much or that are not allowed the opportunity to range. If I had to choose to supplement with just one feed it would be a layer feed rather than the corn.